G Protein-coupled receptors constitute a super family of cell surface proteins. β-arrestin 1 and 2 are widely expressed intracellular adaptor and scaffolding proteins that play important roles in G protein-coupled receptor desensitization, internalization, intracellular traf?cking and G Protein-independent signalling. Recent developments in bioluminescence resonance energy transfer （BRET）technology enable monitor the GPCR–β-arrestin complexes in live cells and real time. In concert with a range of experimental tools, investigators can elucidate the ever-expanding roles of β-arrestins in mediating GPCR function, which will be benefit for developing new generation drugs targeting GPCRs.